Pneumatic tire

ABSTRACT

A heavy-duty, radial ply, pneumatic tire having normally flexible sidewall zones, reinforced, rigid bead zones, and transition zones of gradually decreasing stiffness extending outwardly from the bead zones to the sidewall zones. Each side of the tire includes: (1) an inner group of radial carcass plies, the ends of such plies being turned outwardly over a bead wire bundle and being staged so as to terminate at least at two different points in the transition zone; (2) an outer group of radial carcass plies, the ends of such plies being turned inwardly over the bead wire bundle and being staged so as to terminate at least at two different points in the bead zone; (3) a plurality of chafers having staged upper ends terminating at a plurality of different points in the transition zone; and (4) one or more flippers which encircle the bead wire bundle and at least a portion of an apex strip adjacent to the bead wire bundle.

iUnited @tates @atent Devienne at al. 1 Feb. 11, 11972 [54] PNEUMATICTIRE 3,254,694 6/1966 Sparks et al ..l52/362 R [72] Inventors: ndreDevieggte; )Jzan Trzepaez, both of FOREIGN PATENTS OR ppu s ompregne iserance 879,365 6/1953 Germar ..152 362 CS [73] Assignee: UniroyalEnglebert France S.A., Neuilly My Same France Primary ExaminerArthur L.La Point {22] Filed: No 19 1969 Assistant Examiner-Robert SaiferAttorney-Jack Posin [21] Appl. No.1 878,112

[57] ABSTRACT l l Foreign Appucauan ority Data A heavy-duty, radial ply,pneumatic tire having normally flexi- Dec. 31, 1968 France ..1s2,994 blesidewall i rigid bead mnesnand zones of gradually decreasing stiffnessextending outwardly n from the bead zones to the sidewall zones. Eachside of the tire [52} us. el "152/356 152/362 [51] int (3L N 15/06includes: (1) an inner group of radial carcass plies, the ends of [58]Field Giana; .i'ii'ifs, 356, 362 9 Plies W a bead f bundle being stagedso as to terminate at least at two different points 56 R in thetransition zone; (2) an outer group of radial carcass 1 flames Citedplies, the ends of such plies being turned inwardly over the UN D STATESPATENTS bead wiefibundle and beingtlstaieddso as to tgrminate alt least6 at two i erent points in e ea zone; a plura ity of 2:555 64 4/1939schlPpel "295/12 chafers having staged upper ends terminating at aplurality of 2 838 058 5/1959 Man t 1 1 2 362 J different points in thetransition zone; and (4) one or more 3,052w75 9/1952 y JIM flipperswhich encircle the bead wire bundle and at least a par- 3 077 915 2/1963Weber 152/355 524574 55 4/1966 Lewis 152/356 tion of an apex strip adacent to the bead wire bundle. 2,053,105 l2/l936 King ..152/356 10Claims, 2 Drawing Figures PATENTEDFEB um 3.1638105 B Jaw 7kZEP 4EZ.

PNEUMATIC TIRE This invention relates to pneumatic tires and, moreparticularly, to heavy-duty, radial ply, pneumatic tires havingreinforced bead zones.

In radial ply tire casings one or more carcass plies having radiallyoriented cords, are folded about axially spaced bead wire bundles.Although the radial carcass plies impart to the casings a flexibilityand pliaricy which enhances the comfort of the user, this veryflexibility makes it necessary to stiffen the tread zones of the casings(with one or more circumferential belts) to enhance their resistance totransverse deformation, and to stiffen the bead zones of the casings inorder to provide for more permanent seating of the beads on theirrespective wheel rims.

With reference more particularly to the reinforcement of the bead zones,experience teaches that when tire casings reach a certain size, thereinforcement of the bead zones constituted by the folding of a radialply or plies around bead wire bundles proves to be inadequate.Therefore, it has long been the practice in the tire art to disposeadditional reinforcing elements, known in the trade as chafers" andflippers," in the bead zones of heavy-duty radial ply tires. Theseelements, comprising circumferential reinforcing strips, make itpossible to obtain beads zones having the desired rigidity.

Experience also teaches that when tire casings with rigid beads mustconcurrently withstand heavy loads and substantial deformations, theydeteriorate very rapidly in that portion of the casing whichinterconnects the pliant and flexible casing sidewall portions with therigid bead areas of the casings. Studies and tests have shown that thisdeterioration can be significantly reduced by creating, between therigid bead zones of the casing and the zones of greatest flexibility inthe sidewalls, transitions zones of smoothly varying rigidity in whichthe rigidity of the casing gradually decreases from the bead zones tothe corresponding sidewalls.

The present invention, therefore, has for its primary object theprovision of a heavy-duty, radial ply tire casing having at each sidethereof a flexible sidewall, a reinforced rigid bead zone, and atransition zone of gradually decreasing stiffness extending outwardlyfrom the bead zone to the point, at sub stantially midheight of thecasing sidewall, where normal flexibility and pliancy of the sidewalloccurs.

Further objects and advantages of this invention will become apparent asthe following description proceeds.

Briefly stated, and in accordance with one embodiment of this invention,there is provided a tire casing, comprising: (1) an inner group ofcarcass plies having radially oriented cords, the marginal portions ofthe plies being folded about respective axially spaced beads wirebundles, from the inside to the outside of the casing, the ends of theplies being at least partially staged between midheight andquarter-height of the casing, measured from the base of the bead zone;(2) an outer group of carcass plies having radial cords, the marginalportions of the plies being wrapped, from the outside to the inside ofthe casing, about both the respective bead wire bundles and theaforesaid marginal portions of the inner group of carcass plies; (3) atleast two reinforcing chafers positioned outwardly of the outer group ofradial carcass plies in each bead zone, the chafers having cords thereinwhich are crossed from one chafer to the other, the upper end of one ofthe chafers being situated at or below the level of the mean height ofthe corresponding turnups of the plies in the inner group of carcassplies, the upper end of the other chafer being spaced from the upper endof the first chafer and being situated between the upper level of thecorresponding bead wire bundle and the upper end of the first cbafer;(4) at least one flipper positioned within the folded marginal portionof the inner group of radial carcass plies in each bead zone, each suchflipper enveloping the bead wire bundle and at least a portion of arubber apex filler element in each such bead zone.

The term rubber is used in a generic manner in this specification indescribing and claiming materials which may be used with this invention,and it will be understood that this term is meant to include not onlynatural rubber, but synthetic rubbers and rubberlike materials which maybe suitable for use in the manufacture of pneumatic tires. The termcords" is used in a generic manner in this specification in describingand claiming materials which may be used with this invention, and itwill be understood that this term has reference to generallyinextensible, substantially nonwoven, filaments, cords or cables made ofany of a number of conventional either metallic or nonmetalliccord-forming materials which are normally used or may become useful as areinforcement means in a pneumatic tire (e.g., cotton, rayon, nylon,polyester, glass fiber, steel wire, and the like.

Although the specification concludes with claims particularly pointingout and distinctly claiming the subject matter which is regarded as theinvention, it is believed that the in vention will be better understoodfrom the following descrip tion, taken in conjunction with theaccompanying drawings, in which:

FIG. l represents a schematic view in radial section of a portion of atire casing made in accordance with this invention, the viewillustrating that portion of the casing which extends from one of thebeads to approximately the midcircum ferential plane of the casing; and,

FIG. 2 is an enlarged view, similar to FIG. 1, showing the bead zone,the transition zone and a portion of the sidewall zone ofthe tire casingin greater detail than in FIG. 1.

Referring to FIG. 1, a radial ply tire casing made in accordance withthe present invention comprises an inner group 1 of radial plies and anouter group 2 of radial plies, the plies in group 1 being foldedoutwardly around a bead wire bundle 3 and up to a height of about halfthe height of the casing, the plies in group 2 being folded inwardlyaround the bead wire bundle 3, below the plies of group 1. The tirecasing further includes a lateral reinforcement in the bead zone thereofconstituted by at least two chafers 4 and S which are provided withcords therein of low stretchability, for example metal, and by one ormore flippers 6 which surround the bead wire bundle 3 and at least aportion of a rubber apex filler element 7 associated with the bead wirebundle, the flippers 6 being disposed inside the folded portions of theplies of inner group 1.

Referring more particularly to FlG. 2, the inner group of radial plies 1comprises, for example, four plies la, lb, 1c, and 1d, these plies beingfolded at their marginal portions around the bead wire bundle 3 andstaged, regularly or not, over a height equal to one-quarter of theheight H of the casing, the end of the outermost ply la, being placedsubstantially at midheight l-l/2 of the casing, the end of the innermostply ld being placed at a distance of about l-l/4 from the base of thebead, the ends of the plies lb and 1c occupying intermediate positionsbetween the ends of plies la and 1d. The outer group of radial plies 2comprises, for example, four plies 2a, 2b, 2c and 2d, these plies beingfolded at their marginal portions under both the bead wire bundle 3 andthe folded marginal portions of the plies in group 1. The ends of plies2a-2d are preferably staged to terminate at spaced points after passingacross substantially the entire width of the base of the bead zone.

The reinforcing chafers 4 and 5 are constituted by layers of cords ofround, oval or flat cross section having low stretchability, for examplemetal, glass or a natural or synthetic textile material, each layerbeing embedded in rubber having a Shore A hardness of betweenapproximately 65 and The cords of one of the chafers 4 and 5 formcrossing angles with respect to the cords of the other of the chafers,each layer of filamerits, cords or cables forming an angle with a radialplane of the casing of either between 20 and 60 or between 20 and 60preferably either 40 or 40.

The upper (radially outer) ends 4a and 5a of the chafers d and 5 areradially spaced from one another (staged) to insure that there is asmooth and gradual change of flexibility in the transition zone of thecasing, the end 4a of chafcr 4 being situated at, or below, a levelcorresponding to the mean height of the ends of the plies la-ld in groupl, the end 50 of chafer S being spaced from the end 44 and beingsituated between the upper level of bead wire bundle 3 and the level ofthe end 40 of chafer 4. The lower ends 4b and 5b of chafers 4 and 5terminate in that portion of the bead zone which is situated below theupper level of the bead wire bundle 3. The chafers 4 and 5 arepreferably designed to have sufficient rigidity to obviate any need forproviding conventional hard rubber reinforcing cushions in the portionsof the bead zones in which they are located.

A flipper layer, or a group of flipper layers, 6 is disposed about thebead wire bundle 3 and the rubber apex element 7 in order to add to therigidity of the casing in the bead zone. The flippers 6 are preferablyprovided with cords of a material having low stretchability, for examplemetal, glass or a natural or synthetic textile material. Alternatively,the flippers 6 can be comprised of a natural or synthetic textile felt,for example nylon, polyester or glass fiber, loaded with a mixture ofhard rubber having a Shore A hardness of between 70 and 85. The ends ofthe various flipper layers 6 are preferably also staged to terminate atspaced apart points in the transition zone of the casing.

While there has been shown and described what is at present consideredto be the preferred embodiment of this invention, it will be obvious tothose skilled in the art that various changes and modifications may bemade therein without departing from this invention in its broaderaspects. Thus, for example, the folded ends la-la' of the plies in innergroup 1 can be grouped and staged in pairs, the ends la and lb on theone hand, and 1c and M on the other, coinciding to form two stagedsubgroups, or the ends lb and 1c coinciding and being disposed betweenthe ends la and 1d. Similarly, when the lower ply ends of the plies ofgroup 2 are staged in the base of the bead zone, alternative groupings,analogous to those indicated above with respect to the plies of group 1,may be employed. Also, more than two reinforcing chafers 4 and 5 can beutilized, the upper ends of the additional chafers being positioned atthe same level as either chafer end 4a and 5a, or being positionedbetween these two levels, the lower ends of the additional chafers beingpositioned in the bead zone, between the upper level of the bead wirebundle 3 and the base of the bead zone. in addition, the relativedisposition of the chafers can be the reverse of that shown in F IG. 2.in this case the upper end 4a of the inner chafer would be situated atthe lower level and the upper end 5a of the outer chafer would besituated at the higher level of the two chafer end levels illustrated inFIG. 2. Finally, the characteristics of the cords employed in thechafers and flippers, for example their tensile strengths, densities andthicknesses, can be selected as a function of the dimensions of thecasing and/or the loads which they are designed to support, thesecharacteristics perhaps being the same for the chafers and flippersunder some circumstances and different under others.

Accordingly, it is aimed in the appended claims to cover all suchchanges and modifications to the embodiments of the invention describedherein as fall within the true spirit and scope of this invention.

Having thus described the invention, what is claimed as new and desiredto be protected by Letters Patent is:

l. A radial ply pneumatic tire having at each side thereof a rigid beadzone including a bead wire bundle and a rubber apex strip therein, aflexible sidewall zone spaced from the bead zone and a transition zoneof gradually decreasing stiffness extending radially outwardly from thebead zone to the sidewall zone, said tire further comprising:

a. an inner group of carcass plies having substantially radial cords,the ends of said plies being turned up outwardly about the bead wirebundle at each side of the tire, the ends of said plies at each side ofthe tire being staged to terminate at least at two spaced points locatedbetween one half and one quarter of the height of the casing above thebase of the bead zone;

b. an outer group of carcass plies having substantially radial cords,the ends of said lies at each side of the tire being turned inwardlybelow 0th the bead wire bundle and the plies of said inner group at eachside of the tire;

c. a plurality of reinforcing chafers of bias cut cord fabric in eachbead zone positioned axially outwardly of said outer group of carcassplies, the cords of one of said chafers forming crossing angles withrespect to the cords of another of said chafers, the radially outer endof one of said chafers being positioned no further outwardly than themean radius of the ends of the plies in said inner group of carcassplies, the radially outer end of another of said chafers being spacedfrom the radially outer end of said one of said chafers and beingpositioned between the radially outer level of the bead wire bundle insaid bead zone and the level of the radially outer end of said one ofsaid chafers; and

d. eventually one or more flippers in each bead zone, said flipper beingpositioned within the turned up portion of the inner group of saidcarcass plies, said flipper enveloping the bead wire bundle in each beadzone and at least a portion of said apex strip in said zone.

2. A tire as described in claim 1 wherein said flipper completelyenvelops said apex strip in said zone.

3. A tire as described in claim 2 wherein the cords of said chafers areembedded in rubber having a Shore A hardness of between and 4. A tire asdescribed in claim 3 wherein the radially inner ends of said chafers arepositioned between the radialiy outer level of said bead wire bundle andthe radially innermost portion of the bead zone.

5. A tire as described in claim 4 wherein the ends of the plies in theouter group of carcass plies are staged to terminate at least at twospaced points in each bead zone of said tire.

6. A tire as described in claim 5 wherein said flipper com priseselongated cords embedded in rubber having a Shore A hardness of between65 and 80.

7. A tire as described in claim 2 wherein said flippers comprise anatural or synthetic felt loaded with rubber having a Shore A hardnessof between 70 and 8. A tire as described in claim 2 wherein the ends ofsaid flipper are staged to terminate at spaced-apart points in saidtransition zone.

1. A radial ply pneumatic tire having at each side thereof a rigid beadzone including a bead wire bundle and a rubber apex strip therein, aflexible sidewall zone spaced from the bead zone and a transition zoneof gradually decreasing stiffness extending radially outwardly from thebead zone to the sidewall zone, said tire further comprising: a. aninner group of carcass plies having substantially radial cords, the endsof said plies being turned up outwardly about the bead wire bundle ateach side of the tire, the ends of said plies at each side of the tirebeing staged to terminate at least at two spaced points located betweenone half and one quarter of the height of the casing above the base ofthe bead zone; b. an outer group of carcass plies having substantiallyradial cords, the ends of said plies at each side of the tire beingturned inwardly below both the bead wire bundle and the plies of saidinner group at each side of the tire; c. a plurality of reinforcingchafers of bias cut cord fabric in each bead zone positioned axiallyoutwardly of said outer group of carcass plies, the cords of one of saidchafers forming crossing angles with respect to the cords of another ofsaid chafers, the radially outer end of one of said chafers beingpositioned no further outwardly than the mean radius of the ends of theplies in said inner group of carcass plies, the radially outer end ofanother of said chafers being spaced from the radially outer end of saidone of said chafers and being positioned between the radially outerlevel of the bead wire bundle in said bead zone and the level of theradially outer end of said one of said chafers; and d. eventually one ormore flippers in each bead zone, said flipper being positioned withinthe turned up portion of the inner group of said carcass plies, saidflipper enveloping the bead wire bundle in each bead zone and at least aportion of said apex strip in said zone.
 2. A tire as described in clAim1 wherein said flipper completely envelops said apex strip in said zone.3. A tire as described in claim 2 wherein the cords of said chafers areembedded in rubber having a Shore A hardness of between 65* and 80*. 4.A tire as described in claim 3 wherein the radially inner ends of saidchafers are positioned between the radially outer level of said beadwire bundle and the radially innermost portion of the bead zone.
 5. Atire as described in claim 4 wherein the ends of the plies in the outergroup of carcass plies are staged to terminate at least at two spacedpoints in each bead zone of said tire.
 6. A tire as described in claim 5wherein said flipper comprises elongated cords embedded in rubber havinga Shore A hardness of between 65* and 80*.
 7. A tire as described inclaim 2 wherein said flippers comprise a natural or synthetic feltloaded with rubber having a Shore A hardness of between 70* and 85*. 8.A tire as described in claim 2 wherein the ends of said flipper arestaged to terminate at spaced-apart points in said transition zone.
 9. Atire as described in claim 8 and further including a second flipperenveloping said bead wire bundle and said apex strip, the ends of saidsecond flipper being staged to terminate at points in said transitionzone spaced both from each other and from the ends of said firstflipper.
 10. A tire as described in claim 9 wherein said flippers andsaid chafers each comprise elongated cords embedded in rubber having aShore A hardness of between 65* and 80*.